create newsletter email publisher for apple apps

apple/OmnivoreKit/Sources/Models/NewsletterEmails.swift

@@ -0,0 +1,21 @@
+import Foundation
+
+public class NewsletterEmails {
+  public let newsletterEmails: [NewsletterEmail]
+
+  public init(newsletterEmails: [NewsletterEmail]) {
+    self.newsletterEmails = newsletterEmails
+  }
+}
+
+public struct NewsletterEmail {
+  public let id: String
+  public let email: String
+  public let confirmationCode: String?
+
+  public init(id: String, email: String, confirmationCode: String?) {
+    self.id = id
+    self.email = email
+    self.confirmationCode = confirmationCode
+  }
+}

apple/OmnivoreKit/Sources/Services/DataService/Queries/NewsletterEmailsQuery.swift

@@ -0,0 +1,63 @@
+import Combine
+import Foundation
+import Models
+import SwiftGraphQL
+
+public extension DataService {
+  func newsletterEmailsPublisher() -> AnyPublisher<NewsletterEmails, ServerError> {
+    enum QueryResult {
+      case success(result: NewsletterEmails)
+      case error(error: String)
+    }
+
+    let newsletterEmailSelection = Selection.NewsletterEmail {
+      NewsletterEmail(
+        id: try $0.id(),
+        email: try $0.address(),
+        confirmationCode: try $0.confirmationCode()
+      )
+    }
+
+    let selection = Selection<QueryResult, Unions.NewsletterEmailsResult> {
+      try $0.on(
+        newsletterEmailsSuccess: .init {
+          QueryResult.success(result:
+            NewsletterEmails(
+              newsletterEmails: try $0.newsletterEmails(selection: newsletterEmailSelection.list)
+            )
+          )
+        },
+        newsletterEmailsError: .init {
+          QueryResult.error(error: try $0.errorCodes().description)
+        }
+      )
+    }
+
+    let query = Selection.Query {
+      try $0.newsletterEmails(selection: selection)
+    }
+
+    let path = appEnvironment.graphqlPath
+    let headers = networker.defaultHeaders
+
+    return Deferred {
+      Future { promise in
+        send(query, to: path, headers: headers) { result in
+          switch result {
+          case let .success(payload):
+            switch payload.data {
+            case let .success(result: result):
+              promise(.success(result))
+            case .error:
+              promise(.failure(.unknown))
+            }
+          case .failure:
+            promise(.failure(.unknown))
+          }
+        }
+      }
+    }
+    .receive(on: DispatchQueue.main)
+    .eraseToAnyPublisher()
+  }
+}